My game-changer light in 2018 was the Maratac Peanut. I see a lot of other flashlight companies releasing basically the same light, like the Olight i1R someone mentioned earlier, but the brass body of the Maratac looks really good on my key ring and the fact that you can replace the battery is a nice feature. This light was a game-changer for me because previously I was carrying a AAA light in my pocket, where it wasn't really being retained. A lot of people here may cringe to hear me say that I forgot it at home as often as I carried it! The Peanut light got a flashlight on my key ring, so I'll always have it with me, and halved the size of a AAA light for essentially no penalty in brightness.